A radio frequency (RF) signal coupling system, comprising a shunt device and a coupling unit for cooperative engagement with a MV power network and an RF modem. The shunt device has a high voltage terminal connected to an electrical cable of the power network and a low voltage terminal. The coupling unit comprises a signal lead connected to the low voltage terminal of the shunt device, a ground lead connected to earth ground, a coupling transformer and an impedance matching and protection circuitry. The coupling transformer comprises a ferrite ring, a multiple turn primary winding having a first end and a second end, the first end being connected to the signal lead and the second end being connected to the ground lead, and a multiple turn secondary winding having two terminals connected to the impedance matching and protection circuitry for providing the RF signal to the RF modem.